Set Gerrit to 2.15.6

Change-Id: If495b579906bcc93393b4518f6091108e0cd7123
diff --git a/docker/centos7/Makefile b/docker/centos7/Makefile
index de672b7..15c3142 100644
--- a/docker/centos7/Makefile
+++ b/docker/centos7/Makefile
@@ -1,7 +1,7 @@
 # Customise the following variable as Make parameters
 # to produce a yum.repo for a VENDOR distribution
 # Default values are pointing to GerritForge (www.gerritforge.com)
-VERSION=2.15.5
+VERSION=2.15.6
 RELEASE=1
 REPO_VERSION=1
 REPO_RELEASE=2
diff --git a/docker/ubuntu16.04/Makefile b/docker/ubuntu16.04/Makefile
index 15937e2..b2048d5 100644
--- a/docker/ubuntu16.04/Makefile
+++ b/docker/ubuntu16.04/Makefile
@@ -1,7 +1,7 @@
 # Customise the following variable as Make parameters
 # to produce a yum.repo for a VENDOR distribution
 # Default values are pointing to GerritForge (www.gerritforge.com)
-VERSION=2.15.5
+VERSION=2.15.6
 RELEASE=1
 VENDOR=GerritForge
 VENDOR_LC=$(shell echo $(VENDOR) | tr A-Z a-z)
diff --git a/fpm/Makefile b/fpm/Makefile
index edfd36b..82c72e7 100644
--- a/fpm/Makefile
+++ b/fpm/Makefile
@@ -1,4 +1,4 @@
-VERSION=2.15.5
+VERSION=2.15.6
 URL=https://gerrit-releases.storage.googleapis.com/gerrit-$(VERSION).war
 CI_URL=https://gerrit-ci.gerritforge.com
 RELEASE=1
diff --git a/macOS/Makefile b/macOS/Makefile
index c35b1cf..ac2e1bb 100644
--- a/macOS/Makefile
+++ b/macOS/Makefile
@@ -1,4 +1,4 @@
-VERSION := 2.15.5
+VERSION := 2.15.6
 
 all: server